CUE (pronounced like the letter ‘Q’) stands for clear and unmistakable error. Though they are often referred to as “CUE claims,” CUEs are not actually claims. Rather, CUE is used as shorthand for “request for revision based on clear and unmistakable error.”
Essentially, CUEs are a way for a veteran to attack a final decision from the VA that was never appealed. In order to do this, the veteran must show that the decision in question contained a clear and unmistakable error in fact or error in law.